This invention relates to an electromagnetic repulsion drive switching device for closing/opening a pair of contacts by a drive force utilizing an electromagnetic repulsion.
FIG. 22 is a construction diagram of an electromagnetic repulsion drive switching device of the prior art, and FIG. 23 is a drive circuit diagram of FIG. 22.
FIG. 22 shows the state in which a stationary contact 1a and a movable contact 1b of a vacuum valve 1 are opened (or parted) so that individual terminals 2a and 2b are xe2x80x9copenxe2x80x9d. A capacitor 3 is charged to a predetermined voltage from a charging power source 4 through a charge resistor 5. When a contact-closing thyristor switch 7a is turned xe2x80x9cONxe2x80x9d with a contact-closing gate signal from a gate pulse unit 6, a pulsating drive current flows from the capacitor 3 to a contact-closing coil 8a so that a magnetic field is generated. As a result, an induction current is so generated in a repulsion member 9 that a magnetic field reversed from the magnetic field of the coil 8a is generated. By the interactions between the magnetic field generated by the contact-closing coil 8a and the magnetic field generated by the repulsion member 9, this repulsion member 9 receives an electromagnetic repulsion from the coil 8a. The movable contact 1b, as integrated with the repulsion member 9 by the electromagnetic repulsion force, moves upward in FIG. 22 to close (or contact)the individual contacts 1a and 1b. 
Since the electromagnetic repulsion drive switching device of the prior art has the construction thus far described, the several characteristics of an electrolytic capacitor to be used as the capacitor 3 generally vary with the working temperature. As a result, the drive current flow through the individual coils 8a and 8b fluctuates and raises a problem that the electromagnetic repulsion force is unstable.
Here: numeral 10 designates a reflux diode; numeral 11 a discharge resistor; and numeral 12 a voltage detector.
FIG. 24(a) is a temperature characteristic diagram of the electrostatic capacitance of the capacitor 3; FIG. 24(b) is a temperature characteristic diagram of an equivalent series resistor of the capacitor 3; FIG. 24(c) is a temperature characteristic diagram of the drive current peak value of the individual coils 8a and 8b; and FIG. 24(d) is an explanatory diagram illustrating waveforms of the drive currents of the individual coils 8a and 8b. 
FIG. 24(a) is a temperature characteristic diagram of the electrostatic capacity of the capacitor 3; FIG. 24(b) is a temperature characteristic diagram of an equivalent series resistor of the capacitor 3; FIG. 24(c) is a temperature characteristic diagram of the drive current peak value of the individual coils 8a and 8b; and FIG. 24(d) is an explanatory diagram illustrating waveforms of the drive currents of the individual coils 8a and 8b. 
In FIG. 24(a), the electrostatic capacitance of the capacitor 3 is decreased by 20% at the working temperature of xe2x88x9220xc2x0 C., as compared with that at +20xc2x0 C. In FIG. 24(b), the equivalent series resistor of the capacitor 3 is increased at xe2x88x9220xc2x0 C. to about three times as high as that at +20xc2x0 C. If the range of the drive current peak value, within which the precise actions are made within the working temperature range from xe2x88x9220xc2x0 C. to +40xc2x0 C., is the xe2x80x9cworking rangexe2x80x9d of FIG. 24(c), a decrease of about 20% occurs at xe2x88x9220xc2x0 C. from that at +20xc2x0 C. The waveforms are illustrated in FIG. 24(d).
In FIG. 24(d), numeral 13a designates the drive current of the capacitor 3 at +20xc2x00 C., and numeral 13b designates the drive current of the capacitor 3 at xe2x88x9220xc2x0 C. Thus, a reliably workable drive current peak value cannot be obtained on the low temperature side. If the working temperature of the capacitor 3 rises, on the other hand, the drive current increases to raise the electromagnetic repulsion force. There arises another problem that the mechanical load is augmented.
This invention has been conceived to solve the aforementioned problems and has an object to provide an electromagnetic repulsion drive switching device which is enabled to open/close the contacts precisely by confining the drive current for a contact-closing coil and a contact-opening coil within a predetermined range even if the working temperature of a capacitor changes.
According to this invention, there is provided an electromagnetic repulsion drive switching device in which a contact-closing coil and a contact-opening coil are arranged to confront a repulsive member having a conductivity, and in which a drive current is fed to a selected one of the individual coils from a capacitor charged to a predetermined charge voltage by a charging power source, so that a stationary contact and a movable contact are brought into and out of contact by a repulsion force of the electromagnetic force generated between the coil and the repulsion member. The electromagnetic repulsion drive switching device comprises voltage control means for controlling the output voltage of the charging power source so that the peak value of the drive current may fall within a predetermined range with respect to a temperature change of the capacitor. By controlling the fluctuations of the electrostatic capacity with respect to the temperature change of the capacitor with the output voltage of the charging power source, the peak value of the drive current is enabled to fall within the predetermined range to stabilize the switching actions.
In this invention, on the other hand, the voltage control means controls the output voltage of the charging power source such that when the working temperature of the capacitor is a first temperature for the reference, the charge voltage is set to Vc, and the drive current is set to I, and such that when the working temperature of the capacitor is a second temperature and the drive current is xcex1xc2x7I, the charge voltage of the capacitor is set to Vc/xcex1. As a result, the switching actions can be stabilized by confining the drive current within the allowable working range.
In this invention, on the other hand, the voltage control means controls the charge voltage of the capacitor as a product of the reference voltage and a resistance ratio, so that the resistance of a resistor having a temperature dependency is confined in a formula for calculating the resistance ratio. As a result, the switching actions can be stabilized by confining the drive current within the allowable working range.
In this invention, on the other hand, the resistor having the temperature dependency has a resistance having negative characteristics with respect to the temperature, and a voltage suppression element for suppressing the voltage is connected in parallel with the resistor. Even if the capacitor becomes lower than the limit working minimum temperature, the voltage suppression element can act to control the impedance at the two ends of the resistor so that the charge voltage of the capacitor can be set to the allowable maximum impressed voltage or lower.
In this invention, on the other hand, the repulsion member is made of a flat metal member and there enables a simple structure.
In this invention, on the other hand, the repulsion member is a repulsion coil for generating an electromagnetic force in the direction opposed to that of an electromagnetic force which is generated by a selected one of a contact-closing coil and a contact-opening coil. As a result, the electromagnetic force can be easily adjusted.
In this invention, on the other hand, the temperature of the capacitor is controlled to fall within a predetermined range by temperature control means so that the peak value of the drive current of the capacitor may fall within the allowable working range. With this construction, too, the switching actions can be stabilized.
In this invention, on the other hand, the temperatures of the individual coils are controlled by temperature control means so that the fluctuations of the impedance of the capacitor may be compensated by detecting the temperature of the capacitor. With this construction, too, the drive current of the capacitor can be confined within the allowable working range to stabilize the switching actions.
In this invention, on the other hand, a variable impedance is connected individually with the individual coils and is controlled so that the peak value of the drive current may fall within a predetermined allowable working range with respect to a temperature change of the capacitor. With this construction, too, the switching actions can be stabilized.
In this invention, on the other hand, the variable impedance includes a variable inductance and a variable resistor. The variable inductance and the variable resistor are controlled to confine the peak value of the drive current within the predetermined allowable working range with respect to the temperature change of the capacity, so that the switching actions can be stabilized.
In this invention, on the other hand, the variable resistor is connected in parallel with the capacitor, and the entire impedance is controlled to a predetermined value so that the peak value of the drive current may fall within a predetermined allowable working range with respect to a temperature change of the capacitor. With this construction, too, the switching actions can be stabilized.
In this invention, moreover, a resistor having a temperature dependency is connected individually with the individual coils to compensate the impedance due to the temperature change of the capacitor so that the peak value of the drive current may fall within a predetermined range. With this construction, too, the switching actions can be stabilized.